Duchess Kate's first appearance since announcing she's pregnant with baby No. 3 has left her fans concerned about her health.

The 35-year-old glowed in a lace Temperley London frock -- a look that got rave reviews from fashionistas and non-fashionistas alike -- but she received unwarranted remarks from body shamers who commented on her figure.

Internet trolls took to social media to call Prince William's wife "too thin."

"I can't believe she's prego," one commenter said on Kensington Palace's Instagram account. Another asked: "I thought she was pregnant?"

However, other fans also expressed genuine concern about the Duchess' health. The mother of two has been suffering from hyperemersis gravidarum, a severe form of morning sickness.

"She's so thin. I hope she's doing better," one user wrote.

Lesley Gilchrist, a practicing midwife and co-founder of "My Expert Midwife," revealed to DailyMail that "bump shaming" can cause anxiety for expectant mothers.

"Bump shaming can really damage a woman's body confidence and cause needless worry and anxiety over the health of their baby. It's important to remember that the bump size is just the size of the baby's "packaging" and has no bearing on the size of their baby," she told the outlet.

The Duchess of Cambridge has stayed out of the spotlight since announcing her pregnancy -- even missing George's first day of school -- due to her morning sickness.

The condition affects about one in every 200 pregnancies and results in severe nausea, dehydration, and low blood pressure, among other things.

Prince William revealed that Kate has been trying to eat ginger biscuits to alleviate her morning sickness. The Duke also hinted that their bundle of joy maybe coming sooner rather than later while talking to a midwife.